A common frustration is the lack of fast progress on modernizing the product. It's a small company, so one might assume that's why, but I've since worked at massively larger enterprise companies with the exact same problem. When one major client pays the bills, the reality is that most of your man hours have to go to what's important to that company.
One of the biggest negatives I would point out is the lack of a career path, and the lack of any formalized review and development process. In a way, you can turn this around to a positive; you need to be proactive and take your fate into your own hands as far as raises and new job opportunities, and that's actually an invaluable life skill.
But that lack of structure can be very off-putting, especially for people who are just entering the working world. TL has a lot of those, and I suspect most of the negative reviews here are from people who just entered the workforce from college, without any other companies to compare it to.
I can tell you from having worked at a variety of jobs, TL doesn't deserve its current rating. There are absolutely some things I would change if I went back there, but the fact remains that I WOULD consider going back there someday.
